Mermaid Man and Barnacle Boy – Costuming in the Round



My first thought for costumes when I heard the theme for Portland’s 2014 Run Like Hell was “Under the Sea,” was to do Marlin and Dory from Finding Nemo. But after weeks of looking at examples, I just couldn’t get started. I realized the problem was not with the difficulty of making fish costumes (which is not a small problem), but with a lack of excitement for the concept. So I started looking for undersea characters that I could get excited about, and quickly decided on Mermaid Man and Barnacle Boy from SpongeBob Squarepants.


Mermaid Man and Barnacle Boy are semi-retired superheroes with diminished powers due to their advanced ages. This seemed ideal for my husband and I; age-appropriate costumes at last! And I have been struggling with asthma this year, so my running powers are certainly diminished. Plus I love costumes that appeal to kids and make people laugh, and these two are the funniest heroes under the sea. They really put the “silly” in Run Silly!

MerMans1 MerMans2

My next step was to look at what costumes had already been done for these characters. I felt that the missing element in the Mermaid Man costumes I saw was his characteristic round body. He is drawn as almost a perfect circle, so I knew that I wanted my costume to capture his round cartoony essence. I started by trying to figure out a structure that would be a smooth globe that I could cover with fabric. But I was stumped at how to achieve a lightweight sphere until I came upon this pumpkin costume:


AHHH! I could make sections of fabric over foam and attach them together to make a circle, rather than try to make a circle from foam and then cover it seamlessly with fabric. For my body “model,” I bought a 75cm exercise ball ($10 at Walmart!). I plotted out a pattern on the ball with masking tape. This gave me rough dimensions for the pattern pieces that I cut out of wrapping paper. What you don’t see in the photo is the Dollar Store hula hoop that I used to make sure the center of the circle stayed round. More on this later.

BallPattern3a BallPattern3b

For the foam, I needed something that would have enough structure while being pliable enough to curve easily. Joann Fabrics had the perfect product, Foamology Household Foam. It is available in BIG sheets, I bought the 48″ by 96″ size and ended up using most of the roll between the two costumes. It is spendy at the regular price ($69), but you regular Joann’s customers know how to work those coupons. I got it for about $28. While at Joann, I also picked up most of the fabric I needed. I did have to order the green mermaid fabric online. I wanted the “Jumbo” Fish Scale lycra, since Mermaid Man is a jumbo kind of guy.

Now that I had patterns, foam, and fabric, it was just a matter of cutting and sewing each section separately, then sewing the sections together. For each section, there were two fabric pieces, inside and out, and a foam section. The fabric was sewn with the right sides facing out and the foam in between, with the seams on the outside. Once all the sections were done, I sewed these seams together with the new combined seams ending up inside the costume. I put on a neckband just like I would for a regular t-shirt. It was bulky, but I did manage to do it all on the machine.

MermanSewinga MermanSewingb

Once I had all the sections for the shirt done, I sewed a channel in the “waist” for the hula hoop. I took off the wrapping from the hoop and removed the rocks from inside. I didn’t want the hula hoop sound, just the shape. Then I opened up the hoop and put it through the channel so it was enclosed inside the waist.

MermanSewing2a MermanSewing2b

I moved on to the pants. I used the same patterns of sections as the shirt, but cut the foam first to figure out where the leg openings would be. I tacked the sections together with masking tape and tried them on, trimming as I went. When I was happy with how they were fitting, I used the foam sections as patterns to cut the fabric. Because I was using the spendy mermaid lycra for the pants, I used plain black lycra for the inner fabric.


Since the bottom of the pants was a finished edge, I sewed that with the right sides together and then turned the right sides to the outside and sewed the side seams. I left the top edges open to slip in the foam sections after I had sewed all the pants sections together.



When the pants were together, I hand-sewed the pants to the shirt. The seam didn’t have to be perfect since it would be covered with the wide belt. The last tricky part was cutting the holes for my arms. I tried it on, measured, measured again, took a deep breath, and cut the holes. Whew, OK fit. I hand-sewed the edges of the armholes inside.

MermanSewing4a MermanSewing4b

The belt was made from a long strip of foam covered with yellow Lycra. I hand-sewed it to the shirt and pants. I plan to add pockets to it so I have someplace to carry the keys to the Invisible Boatmobile. The “M” symbol was a lucky find at Michaels, a cardboard letter that I painted to match. I bought a foam shell “bra” and took it apart and painted it lavender. My “bra” straps are elastic I hand-sewed on. I was going to make gloves, but found these green ones that are a pretty good match.

I made a long sleeve shirt from the same orange lycra as the outer body. I also made the green lycra tights. I have a serger which makes working with lycra a breeze. But you could just use a stretch stitch or even zig zag on a regular sewing machine and get good results.


So that is the basics of how I managed to make a round-body costume. Hopefully you will find something that will help in your own project.